The development and regeneration of sensory appendages, the abdominal cerci of the house cricket Acheta domesticus, will be analyzed with anatomical, cytological and electrophysiological methods. We expect to expand the set of "rules" for neural circuit assembly which we have already started to develop, looking especially towards features common to both insect and vertebrate systems. The pattern of projection of cercal sensilla upon identified and intracellularly marked neurons of the abdominal ventral nerve cord can be analyzed by sensitive physiological techniques. The capacity of grafted cerci to establish connections with ganglia which had no cercal input during development will permit a comparison of embryological and regenerative sensory development. Analysis of the projections of rotated and exchanged cerci will yield a description of the role of appendage and body axes in the establishment of orderly projections. Heterotopic grafts of abdominal cerci to thoracic leg stumps will allow comparison of synapse formation between the same sets of cells but in two widely divergent regions of the post-synaptic neurons.